Sampling of inner tissue on humans and animals, so called biopsy, has become increasingly common. Using thick needle punctuation one can for example take out samples from deeply located organs, such as the liver or the kidneys. This kind of sampling, which is a very mild treatment, is usually carried in such a way that a doctor inserts a needle assembly through the skin and to the desired sampling location. The needle assembly comprises a hollow outer needle and a therewithin slidably provided inner needle. The inner needle has a pointed front portion, and is near the point provided with a hollow for receiving the tissue sample. The sampling itself is carried out in such a way that the inner needle is first pressed slightly inwards from the initial position, such that the surrounding tissue expands into the hollow provided in the inner needle. Thereafter the hollow outer needle is pushed forward to cover the inner needle thus cutting out a tissue sample, which thereby is collected in the hollow provided in the inner needle, and retained by the surrounding outer needle. Then the entire needle assembly containing the collected tissue sample is withdrawn, whereafter the sample can be taken out and analyzed. The sampling procedure is commonly monitored using ultra sonic equipment, to ensure the sampling is carried out correctly.
Such sampling is mostly carried out completely manually, demanding that two doctors participate, one of whom operates the ultra sonic equipment, and the other carrying out the sampling, i.e. a very work intensive procedure. In addition the sampling demands great skill and precision when handling the needle assembly, especially for coordinating the movements of the two needles, such that the entire needle assembly is first brought to the desired initial position, whereafter the inner needle is pushed forward and finally that the outer needle is moved forward over the inner needle, simultaneously cutting off the tissue sample. It can easily happen that the inner needle inadvertently is withdrawn during the cutting phase, with the consequence that none or too small an amount of tissue is collected in the hollow in the inner needle.
Thus there is a great need for biopsy devices, demanding the participation of just one doctor, and enhancing the security when operating the needle assembly. An attempt to solve this problem is described in Se-A-No.-8202061-1, with the same applicants as the present application, the inventive idea of which resides in placing the needle assembly in a box, in which box there are provided propelling means for propelling the outer and inner needles, such that they carry out the above mentioned coordinated movements when the needle assembly has been located to the correct sampling position in the body. The needles are brought to carry out the desired movements in that the operator actuates a release mechanism outside of the box.
This known device constituted a great technical progress, since it made possible both one-hand operation during sampling (the doctor could manipulate the ultra sonic equipment with one hand and the sampling device with the other hand), and also enchanced security and precision when sampling (the relative movements of the needles were automatically controlled by the device). In spite of this the known device has shown several drawbacks. Among other things it has certain deficiencies regarding stability, and the procedures for placing the propelling means for the needles under tension and for loading the needle assembly, are relatively complicated and are being carried out in separate steps, whereby the propelling means must be tightened manually or with the aid of special tools. Further, the known device is deficient concerning security (e.g. there is a risk for inadvertent release of the device), and guiding of the needle assembly.